US president Barack Obama has announced a $100 million plan to map the billions of neurons at work in the human brain.

The US is known for big ideas like the moon landing, the space shuttle program and the personal computer, and Mr Obama says the mapping is "the next great American project".

The plan will speed up development of new technologies that will help researchers create what is called dynamic brain imaging.

"As humans we can identify galaxies light years away, we can study particles smaller than the atom, but we still haven't unlocked the mystery of the three pounds of matter that sits between our ears," he said.

As humans we can identify galaxies light years away, we can study particles smaller than the atom, but we still haven't unlocked the mystery of the three pounds of matter that sits between our ears.

Barack Obama

"So there is this enormous mystery waiting to be unlocked, and the BRAIN Initiative will change that by giving scientists the tools they need to get a dynamic picture of the brain in action and better understand how we think and how we learn and how we remember.

"And that knowledge could be - will be - transformative."

The brain is the least understood part of the human body.

We have a rudimentary idea of how it works, and why things go wrong, but the bigger questions like how we generate thoughts are still a mystery.

Answering them will be a big task to say the least.

"Of course, none of this will be easy. If it was, we would already know everything there was about how the brain works, and presumably my life would be simpler here," Mr Obama said.

"But think about what we could do once we do crack this code."

I think this really is one of those great projects that's going to change the world.

Neurologist Zachary Litvak

Zachary Litvak, a neurologist at George Washington University where he is also an assistant professor, says the project is equivalent in scale and potential impact to the moon mission.

"I think this really is one of those great projects that's going to change the world," he told The World Today.

"Just like Apollo, just like the genome project, you are going to see technological developments that are going to spill over into other areas.

"So this isn't just limited to medicine or neuroscience. It's one of those initiatives where we don't exactly know where we're going to end up."

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